CONVERSION OF RECENT-ONSET ATRIAL-FIBRILLATION TO SINUS RHYTHM - EFFECTS OF DIFFERENT DRUG PROTOCOLS

In a population of 417 hospitalized patients, the efficacy and safety of different drug regimens administered to convert atrial fibrillation (AF) of recent onset (less than or equal to 7 days duration) to sinus rhythm were evaluated. All patients were in NYHA Class less than or e qual to 2, and free of heart failure. They were randomly allocated to treatment with placebo in 221 patients; TV amiodarone, 5 mg/kg bolus, followed by 2.8 g/24 hours in 51 patients; IV propafenone, 2 mg/kg bol us, followed by 0.0078 mg/kg/min in 57 patients; p.o. propafenone, 600 mg p.o. in a single dose in 119 patients; and p.o. flecainide, 300 mg p.o. in (7 single dose in 69 patients. All patients were continuously monitored by Holter EGG, and the number of conversions to sinus rhyth m was measured at 1, 3, and 8 hours. Results: (1) IV propafenone resul ted in a higher conversion rate within 2 hour compared with the oral l oading regimens of propafenone or flecainide, but the conversion rates at 3 and 8 hours were comparable, approximately 75% at 8 hours; 2) IV amiodarone was not different from placebo until 8 hours when it was a ssociated with 57% of conversions; (3) conversion to sinus rhythm at 8 hours was observed in 37% of the placebo treated patients. Serious ad verse effects occurred in few patients: two patients treated with flec ainide and one treated with IV propafenone experienced left ventricula r decompensation; one patient treated with placebo and two treated wit h flecainide had atrial flutter with rapid ventricular response. In co nclusion, single-dose, oral loading with propafenone or flecainide are acceptable alternatives to conventional drug regimens in selected hos pitalized patients. In addition, the measure of a placebo effect is ma ndatory in studies of recent-onset AF.